WASHINGTON (CNN) - President Obama celebrated his 48th birthday Tuesday by... meeting with the Senate Democratic Caucus. But he also marked the occasion by accepting a happy birthday call from Russian President Dmitri Medvedev. And he stopped by the briefing room to greet veteran White House scribe Helen Thomas, also celebrating a birthday today (her 89th.) Thomas began reporting from the White House in 1960 - the year before Obama was born.